
<!DOCTYPE HTML>
<html lang="" >
    <head>
        <meta charset="UTF-8">
        <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
        <title>New Axes · GitBook</title>
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="description" content="">
        <meta name="generator" content="GitBook 3.2.2">
        <meta name="author" content="chartjs">



    <link rel="stylesheet" href="../gitbook/style.css">




                <link rel="stylesheet" href="../gitbook/gitbook-plugin-search-plus/search.css">



                <link rel="stylesheet" href="../gitbook/gitbook-plugin-highlight/website.css">



                <link rel="stylesheet" href="../gitbook/gitbook-plugin-fontsettings/website.css">








        <link rel="stylesheet" href="../style.css">

















    <meta name="HandheldFriendly" content="true"/>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    <link rel="apple-touch-icon-precomposed" sizes="152x152" href="../gitbook/images/apple-touch-icon-precomposed-152.png">
    <link rel="shortcut icon" href="../gitbook/images/favicon.ico" type="image/x-icon">


    <link rel="next" href="contributing.html" />


    <link rel="prev" href="charts.html" />


    <link rel="stylesheet" href="../gitbook/gitbook-plugin-chartjs/style.css">
    <script src="../gitbook/gitbook-plugin-chartjs/Chart.bundle.js"></script>
    <script src="../gitbook/gitbook-plugin-chartjs/chartjs-plugin-deferred.js"></script>


    </head>
    <body>

<div class="book">
    <div class="book-summary">


<div id="book-search-input" role="search">
    <input type="text" placeholder="Type to search" />
</div>


                <nav role="navigation">



<ul class="summary">









        <li class="chapter " data-level="1.1" data-path="../">

                <a href="../">


                    Chart.js

                </a>



        </li>

        <li class="chapter " data-level="1.2" data-path="../getting-started/">

                <a href="../getting-started/">


                    Getting Started

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.2.1" data-path="../getting-started/installation.html">

                <a href="../getting-started/installation.html">


                    Installation

                </a>



        </li>

        <li class="chapter " data-level="1.2.2" data-path="../getting-started/integration.html">

                <a href="../getting-started/integration.html">


                    Integration

                </a>



        </li>

        <li class="chapter " data-level="1.2.3" data-path="../getting-started/usage.html">

                <a href="../getting-started/usage.html">


                    Usage

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.3" data-path="../general/">

                <a href="../general/">


                    General

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.3.1" data-path="../general/responsive.html">

                <a href="../general/responsive.html">


                    Responsive

                </a>



        </li>

        <li class="chapter " data-level="1.3.2" data-path="../general/interactions/">

                <a href="../general/interactions/">


                    Interactions

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.3.2.1" data-path="../general/interactions/events.html">

                <a href="../general/interactions/events.html">


                    Events

                </a>



        </li>

        <li class="chapter " data-level="1.3.2.2" data-path="../general/interactions/modes.html">

                <a href="../general/interactions/modes.html">


                    Modes

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.3.3" data-path="../general/options.html">

                <a href="../general/options.html">


                    Options

                </a>



        </li>

        <li class="chapter " data-level="1.3.4" data-path="../general/colors.html">

                <a href="../general/colors.html">


                    Colors

                </a>



        </li>

        <li class="chapter " data-level="1.3.5" data-path="../general/fonts.html">

                <a href="../general/fonts.html">


                    Fonts

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.4" data-path="../configuration/">

                <a href="../configuration/">


                    Configuration

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.4.1" data-path="../configuration/animations.html">

                <a href="../configuration/animations.html">


                    Animations

                </a>



        </li>

        <li class="chapter " data-level="1.4.2" data-path="../configuration/layout.html">

                <a href="../configuration/layout.html">


                    Layout

                </a>



        </li>

        <li class="chapter " data-level="1.4.3" data-path="../configuration/legend.html">

                <a href="../configuration/legend.html">


                    Legend

                </a>



        </li>

        <li class="chapter " data-level="1.4.4" data-path="../configuration/title.html">

                <a href="../configuration/title.html">


                    Title

                </a>



        </li>

        <li class="chapter " data-level="1.4.5" data-path="../configuration/tooltip.html">

                <a href="../configuration/tooltip.html">


                    Tooltip

                </a>



        </li>

        <li class="chapter " data-level="1.4.6" data-path="../configuration/elements.html">

                <a href="../configuration/elements.html">


                    Elements

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.5" data-path="../charts/">

                <a href="../charts/">


                    Charts

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.5.1" data-path="../charts/line.html">

                <a href="../charts/line.html">


                    Line

                </a>



        </li>

        <li class="chapter " data-level="1.5.2" data-path="../charts/bar.html">

                <a href="../charts/bar.html">


                    Bar

                </a>



        </li>

        <li class="chapter " data-level="1.5.3" data-path="../charts/radar.html">

                <a href="../charts/radar.html">


                    Radar

                </a>



        </li>

        <li class="chapter " data-level="1.5.4" data-path="../charts/doughnut.html">

                <a href="../charts/doughnut.html">


                    Doughnut & Pie

                </a>



        </li>

        <li class="chapter " data-level="1.5.5" data-path="../charts/polar.html">

                <a href="../charts/polar.html">


                    Polar Area

                </a>



        </li>

        <li class="chapter " data-level="1.5.6" data-path="../charts/bubble.html">

                <a href="../charts/bubble.html">


                    Bubble

                </a>



        </li>

        <li class="chapter " data-level="1.5.7" data-path="../charts/scatter.html">

                <a href="../charts/scatter.html">


                    Scatter

                </a>



        </li>

        <li class="chapter " data-level="1.5.8" data-path="../charts/area.html">

                <a href="../charts/area.html">


                    Area

                </a>



        </li>

        <li class="chapter " data-level="1.5.9" data-path="../charts/mixed.html">

                <a href="../charts/mixed.html">


                    Mixed

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.6" data-path="../axes/">

                <a href="../axes/">


                    Axes

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.6.1" data-path="../axes/cartesian/">

                <a href="../axes/cartesian/">


                    Cartesian

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.6.1.1" data-path="../axes/cartesian/category.html">

                <a href="../axes/cartesian/category.html">


                    Category

                </a>



        </li>

        <li class="chapter " data-level="1.6.1.2" data-path="../axes/cartesian/linear.html">

                <a href="../axes/cartesian/linear.html">


                    Linear

                </a>



        </li>

        <li class="chapter " data-level="1.6.1.3" data-path="../axes/cartesian/logarithmic.html">

                <a href="../axes/cartesian/logarithmic.html">


                    Logarithmic

                </a>



        </li>

        <li class="chapter " data-level="1.6.1.4" data-path="../axes/cartesian/time.html">

                <a href="../axes/cartesian/time.html">


                    Time

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.6.2" data-path="../axes/radial/">

                <a href="../axes/radial/">


                    Radial

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.6.2.1" data-path="../axes/radial/linear.html">

                <a href="../axes/radial/linear.html">


                    Linear

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.6.3" data-path="../axes/labelling.html">

                <a href="../axes/labelling.html">


                    Labelling

                </a>



        </li>

        <li class="chapter " data-level="1.6.4" data-path="../axes/styling.html">

                <a href="../axes/styling.html">


                    Styling

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.7" data-path="./">

                <a href="./">


                    Developers

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.7.1" data-path="api.html">

                <a href="api.html">


                    Chart.js API

                </a>



        </li>

        <li class="chapter " data-level="1.7.2" data-path="updates.html">

                <a href="updates.html">


                    Updating Charts

                </a>



        </li>

        <li class="chapter " data-level="1.7.3" data-path="plugins.html">

                <a href="plugins.html">


                    Plugins

                </a>



        </li>

        <li class="chapter " data-level="1.7.4" data-path="charts.html">

                <a href="charts.html">


                    New Charts

                </a>



        </li>

        <li class="chapter active" data-level="1.7.5" data-path="axes.html">

                <a href="axes.html">


                    New Axes

                </a>



        </li>

        <li class="chapter " data-level="1.7.6" data-path="contributing.html">

                <a href="contributing.html">


                    Contributing

                </a>



        </li>


            </ul>

        </li>

        <li class="chapter " data-level="1.8" data-path="../notes/">

                <a href="../notes/">


                    Additional Notes

                </a>



            <ul class="articles">


        <li class="chapter " data-level="1.8.1" data-path="../notes/comparison.html">

                <a href="../notes/comparison.html">


                    Comparison Table

                </a>



        </li>

        <li class="chapter " data-level="1.8.2" data-path="../notes/extensions.html">

                <a href="../notes/extensions.html">


                    Popular Extensions

                </a>



        </li>

        <li class="chapter " data-level="1.8.3" data-path="../notes/license.html">

                <a href="../notes/license.html">


                    License

                </a>



        </li>


            </ul>

        </li>




    <li class="divider"></li>

    <li>
        <a href="https://www.gitbook.com" target="blank" class="gitbook-link">
            Published with GitBook
        </a>
    </li>
</ul>


                </nav>


    </div>

    <div class="book-body">

            <div class="body-inner">



<div class="book-header" role="navigation">


    <!-- Title -->
    <h1>
        <i class="fa fa-circle-o-notch fa-spin"></i>
        <a href=".." >New Axes</a>
    </h1>
</div>




                    <div class="page-wrapper" tabindex="-1" role="main">
                        <div class="page-inner">

<div class="search-plus" id="book-search-results">
    <div class="search-noresults">

                                <section class="normal markdown-section">

                                <h1 id="new-axes">New Axes</h1>
<p>Axes in Chart.js can be individually extended. Axes should always derive from Chart.Scale but this is not a mandatory requirement.</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">let</span> MyScale = Chart.Scale.extend({
    <span class="hljs-comment">/* extensions ... */</span>
});

<span class="hljs-comment">// MyScale is now derived from Chart.Scale</span>
</code></pre>
<p>Once you have created your scale class, you need to register it with the global chart object so that it can be used. A default config for the scale may be provided when registering the constructor. The first parameter to the register function is a string key that is used later to identify which scale type to use for a chart.</p>
<pre><code class="lang-javascript">Chart.scaleService.registerScaleType(<span class="hljs-string">&apos;myScale&apos;</span>, MyScale, defaultConfigObject);
</code></pre>
<p>To use the new scale, simply pass in the string key to the config when creating a chart.</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> lineChart = <span class="hljs-keyword">new</span> Chart(ctx, {
    data: data,
    type: <span class="hljs-string">&apos;line&apos;</span>,
    options: {
        scales: {
            yAxes: [{
                type: <span class="hljs-string">&apos;myScale&apos;</span> <span class="hljs-comment">// this is the same key that was passed to the registerScaleType function</span>
            }]
        }
    }
})
</code></pre>
<h2 id="scale-properties">Scale Properties</h2>
<p>Scale instances are given the following properties during the fitting process.</p>
<pre><code class="lang-javascript">{
    left: <span class="hljs-built_in">Number</span>, <span class="hljs-comment">// left edge of the scale bounding box</span>
    right: <span class="hljs-built_in">Number</span>, <span class="hljs-comment">// right edge of the bounding box&apos;</span>
    top: <span class="hljs-built_in">Number</span>,
    bottom: <span class="hljs-built_in">Number</span>,
    width: <span class="hljs-built_in">Number</span>, <span class="hljs-comment">// the same as right - left</span>
    height: <span class="hljs-built_in">Number</span>, <span class="hljs-comment">// the same as bottom - top</span>

    <span class="hljs-comment">// Margin on each side. Like css, this is outside the bounding box.</span>
    margins: {
        left: <span class="hljs-built_in">Number</span>,
        right: <span class="hljs-built_in">Number</span>,
        top: <span class="hljs-built_in">Number</span>,
        bottom: <span class="hljs-built_in">Number</span>,
    },

    <span class="hljs-comment">// Amount of padding on the inside of the bounding box (like CSS)</span>
    paddingLeft: <span class="hljs-built_in">Number</span>,
    paddingRight: <span class="hljs-built_in">Number</span>,
    paddingTop: <span class="hljs-built_in">Number</span>,
    paddingBottom: <span class="hljs-built_in">Number</span>,
}
</code></pre>
<h2 id="scale-interface">Scale Interface</h2>
<p>To work with Chart.js, custom scale types must implement the following interface.</p>
<pre><code class="lang-javascript">{
    <span class="hljs-comment">// Determines the data limits. Should set this.min and this.max to be the data max/min</span>
    determineDataLimits: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{},

    <span class="hljs-comment">// Generate tick marks. this.chart is the chart instance. The data object can be accessed as this.chart.data</span>
    <span class="hljs-comment">// buildTicks() should create a ticks array on the axis instance, if you intend to use any of the implementations from the base class</span>
    buildTicks: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{},

    <span class="hljs-comment">// Get the value to show for the data at the given index of the the given dataset, ie this.chart.data.datasets[datasetIndex].data[index]</span>
    getLabelForIndex: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">index, datasetIndex</span>) </span>{},

    <span class="hljs-comment">// Get the pixel (x coordinate for horizontal axis, y coordinate for vertical axis) for a given value</span>
    <span class="hljs-comment">// @param index: index into the ticks array</span>
    <span class="hljs-comment">// @param includeOffset: if true, get the pixel halway between the given tick and the next</span>
    getPixelForTick: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">index, includeOffset</span>) </span>{},

    <span class="hljs-comment">// Get the pixel (x coordinate for horizontal axis, y coordinate for vertical axis) for a given value</span>
    <span class="hljs-comment">// @param value : the value to get the pixel for</span>
    <span class="hljs-comment">// @param index : index into the data array of the value</span>
    <span class="hljs-comment">// @param datasetIndex : index of the dataset the value comes from</span>
    <span class="hljs-comment">// @param includeOffset : if true, get the pixel halway between the given tick and the next</span>
    getPixelForValue: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">value, index, datasetIndex, includeOffset</span>) </span>{}

    <span class="hljs-comment">// Get the value for a given pixel (x coordinate for horizontal axis, y coordinate for vertical axis)</span>
    <span class="hljs-comment">// @param pixel : pixel value</span>
    getValueForPixel: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">pixel</span>) </span>{}
}
</code></pre>
<p>Optionally, the following methods may also be overwritten, but an implementation is already provided by the <code>Chart.Scale</code> base class.</p>
<pre><code class="lang-javascript">    <span class="hljs-comment">// Transform the ticks array of the scale instance into strings. The default implementation simply calls this.options.ticks.callback(numericalTick, index, ticks);</span>
    convertTicksToLabels: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{},

    <span class="hljs-comment">// Determine how much the labels will rotate by. The default implementation will only rotate labels if the scale is horizontal.</span>
    calculateTickRotation: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{},

    <span class="hljs-comment">// Fits the scale into the canvas.</span>
    <span class="hljs-comment">// this.maxWidth and this.maxHeight will tell you the maximum dimensions the scale instance can be. Scales should endeavour to be as efficient as possible with canvas space.</span>
    <span class="hljs-comment">// this.margins is the amount of space you have on either side of your scale that you may expand in to. This is used already for calculating the best label rotation</span>
    <span class="hljs-comment">// You must set this.minSize to be the size of your scale. It must be an object containing 2 properties: width and height.</span>
    <span class="hljs-comment">// You must set this.width to be the width and this.height to be the height of the scale</span>
    fit: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{},

    <span class="hljs-comment">// Draws the scale onto the canvas. this.(left|right|top|bottom) will have been populated to tell you the area on the canvas to draw in</span>
    <span class="hljs-comment">// @param chartArea : an object containing four properties: left, right, top, bottom. This is the rectangle that lines, bars, etc will be drawn in. It may be used, for example, to draw grid lines.</span>
    draw: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">chartArea</span>) </span>{},
</code></pre>
<p>The Core.Scale base class also has some utility functions that you may find useful.</p>
<pre><code class="lang-javascript">{
    <span class="hljs-comment">// Returns true if the scale instance is horizontal</span>
    isHorizontal: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>) </span>{},

    <span class="hljs-comment">// Get the correct value from the value from this.chart.data.datasets[x].data[]</span>
    <span class="hljs-comment">// If dataValue is an object, returns .x or .y depending on the return of isHorizontal()</span>
    <span class="hljs-comment">// If the value is undefined, returns NaN</span>
    <span class="hljs-comment">// Otherwise returns the value.</span>
    <span class="hljs-comment">// Note that in all cases, the returned value is not guaranteed to be a Number</span>
    getRightValue: <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params">dataValue</span>) </span>{},
}
</code></pre>


                                </section>

    </div>
    <div class="search-results">
        <div class="has-results">

            <h1 class="search-results-title"><span class='search-results-count'></span> results matching "<span class='search-query'></span>"</h1>
            <ul class="search-results-list"></ul>

        </div>
        <div class="no-results">

            <h1 class="search-results-title">No results matching "<span class='search-query'></span>"</h1>

        </div>
    </div>
</div>

                        </div>
                    </div>

            </div>



                <a href="charts.html" class="navigation navigation-prev " aria-label="Previous page: New Charts">
                    <i class="fa fa-angle-left"></i>
                </a>


                <a href="contributing.html" class="navigation navigation-next " aria-label="Next page: Contributing">
                    <i class="fa fa-angle-right"></i>
                </a>



    </div>

    <script>
        var gitbook = gitbook || [];
        gitbook.push(function() {
            gitbook.page.hasChanged({"page":{"title":"New Axes","level":"1.7.5","depth":2,"next":{"title":"Contributing","level":"1.7.6","depth":2,"path":"developers/contributing.md","ref":"developers/contributing.md","articles":[]},"previous":{"title":"New Charts","level":"1.7.4","depth":2,"path":"developers/charts.md","ref":"developers/charts.md","articles":[]},"dir":"ltr"},"config":{"plugins":["-lunr","-search","search-plus","anchorjs","chartjs","ga"],"root":"./docs","styles":{"website":"style.css","pdf":"styles/pdf.css","epub":"styles/epub.css","mobi":"styles/mobi.css","ebook":"styles/ebook.css","print":"styles/print.css"},"pluginsConfig":{"anchorjs":{"icon":"#","placement":"left","visible":"always"},"ga":{"configuration":"auto","token":"UA-28909194-3"},"theme-default":{"styles":{"website":"style.css","pdf":"styles/pdf.css","epub":"styles/epub.css","mobi":"styles/mobi.css","ebook":"styles/ebook.css","print":"styles/print.css"},"showLevel":false},"search-plus":{},"chartjs":{"defaults":null},"highlight":{},"sharing":{"facebook":true,"twitter":true,"google":false,"weibo":false,"instapaper":false,"vk":false,"all":["facebook","google","twitter","weibo","instapaper"]},"fontsettings":{"theme":"white","family":"sans","size":2}},"theme":"default","author":"chartjs","pdf":{"pageNumbers":true,"fontSize":12,"fontFamily":"Arial","paperSize":"a4","chapterMark":"pagebreak","pageBreaksBefore":"/","margin":{"right":62,"left":62,"top":56,"bottom":56}},"structure":{"langs":"LANGS.md","readme":"README.md","glossary":"GLOSSARY.md","summary":"SUMMARY.md"},"variables":{},"gitbook":"3.2.2"},"file":{"path":"developers/axes.md","mtime":"2017-10-28T15:03:49.266Z","type":"markdown"},"gitbook":{"version":"3.2.2","time":"2017-10-28T15:09:53.587Z"},"basePath":"..","book":{"language":""}});
        });
    </script>
</div>


    <script src="../gitbook/gitbook.js"></script>
    <script src="../gitbook/theme.js"></script>


        <script src="../gitbook/gitbook-plugin-search-plus/jquery.mark.min.js"></script>



        <script src="../gitbook/gitbook-plugin-search-plus/search.js"></script>



        <script src="https://cdnjs.cloudflare.com/ajax/libs/anchor-js/3.1.1/anchor.min.js"></script>



        <script src="../gitbook/gitbook-plugin-anchorjs/anchor-style.js"></script>



        <script src="../gitbook/gitbook-plugin-ga/plugin.js"></script>



        <script src="../gitbook/gitbook-plugin-sharing/buttons.js"></script>



        <script src="../gitbook/gitbook-plugin-fontsettings/fontsettings.js"></script>



    </body>
</html>

